traditional: send PDF quote, go back and forth on quoted terms and cost 1..n times, wait for signed PO, call 1..n times reminding them to sign the PO, eventually get signed PO, do work, (at this point client is your BFF and calls you every 5 minutes asking if the work is done yet!), deliver product/service, get at least 100 bug reports on things that differ from the original approved spec/quote but should have been "implied", fix "bugs", send PDF invoice 1..n times, call buyer to remind them to pay invoice 1..n times, get runaround and sent to various accounting people most of whom are on vacation 1..n times, finally get told check is in mail 1..n times, wait 30 days per cycle, sacrifice chicken, call back and find that check was never sent and invoice is lost so repeat steps again, finally check arrives, deposit check in bank
eth: seller defines contract in solidity with various Oraclized callbacks for spec acceptance, delivery of work product(s), final acceptance test execution, and various failure modes that return eth back to the buyer's wallet if necessary, buyer funds contract with eth, acceptance events (e.g. signed PDFs in dropbox, or some git commit, etc) triggers payment to seller's eth wallet, OR on failure cases returns money back to the buyer's wallet
lots of hand wavy stuff here but since we're just discussing ideas...so, in all sincerity, what does this not get you that you are looking for?
EDIT: fix typo